Is my Vitamin D (25-OH) normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal Vitamin D level?
Vitamin D is essential for bone health, immune function, and mood regulation. Over 40% of US adults are deficient. Standard "normal" is 30-100 ng/mL, but longevity researchers recommend 40-80 ng/mL for optimal health outcomes.
| Range | Values |
|---|---|
| Standard Reference | 30–100 ng/mL |
| Optimal | 40–80 ng/mL |
| Longevity Optimal | 40-80 ng/mL |
| Low Risk | < 20 ng/mL |
What causes abnormal Vitamin D levels?
Low vitamin D is caused by insufficient sun exposure (especially at northern latitudes or with darker skin), inadequate dietary intake, malabsorption conditions (celiac, Crohn's), obesity (vitamin D gets sequestered in fat tissue), aging (reduced skin synthesis), and kidney or liver disease that impairs conversion to the active form.
When should you see a doctor?
See your doctor if your vitamin D is below 20 ng/mL (deficient), if you have bone pain or muscle weakness, frequent infections, or fatigue. Also consult before taking high-dose supplements (>5000 IU/day) to avoid toxicity. Retest 3 months after starting supplementation to verify levels.
Where to get a Vitamin D test
Affiliate disclosure: Some links on this page are affiliate links. Otto may earn a commission at no extra cost to you. This does not affect our recommendations.
Related biomarkers
These biomarkers are often tested alongside Vitamin D for a more complete picture.
Frequently asked questions
What is a normal vitamin D level?
How much vitamin D should I take?
Can you have too much vitamin D?
Check all your biomarkers at once
Upload any blood test PDF and get your complete BioMap — a visual map of every biomarker in your panel. Free, instant, no account required.
Upload your labs — Get your BioMapMore biomarker checkers
Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.